DENVER—Colorado businesses that ban guns would be required to provide armed security under a Republican proposal that faces its first test Wednesday.

Republicans face a likely second defeat in less than a week on legislation to prevent mass shootings. The bill being heard Wednesday would require businesses to provide armed security if they ban patrons from carrying concealed weapons.

The bill is opposed by gun-control advocates and business groups and appears destined for hasty rejection. The same Senate committee voted Monday against a measure that would have allowed school employees to carry concealed weapons.

Republican Sen. Kent Lambert says movie theaters and shopping malls that ban concealed weapons should be obligated to provide their own armed security.

Rockies are on pace to lose 93 games this seasonThe Rockies lost three of four in St. Louis and are on pace to lose 93 games as they come home for a three-game series with Seattle before going back on the road again to face Washington.